And here's a bottle picture comparison of the two:
As you can see, the shimmer on Mermaid's Lagoon is much more apparent both in the bottle and on the nail. It was actually hard to photograph the shimmer in the Custom Kicks bottle but with Mermaid's Lagoon it was not a problem at all. As far as the differences in the shimmer, Custom Kicks is much more of a yellow gold whereas Mermaid's Lagoon is much more of a coppery gold. The base color is similar for both but the Custom Kicks base turquoise is slightly lighter.
So... they are definitely different enough for me to justify having them both... and that's the story I'm sticking with. Until next time!